Infiltrating pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal human malignancies, with an overall five-year survival rate of less than five percent. The high mortality rate associated w/ith PDAC is primarily due to the late stage at which disease is diagnosed and the resistance of pancreatic cancer to traditional chemotherapy and radiotherapy treatment approaches. These observations highlight the critical need for early detection of pancreatic neoplasia at a stage where surgical resection can be curative. The major goal of this proposal will be to use state-of-the-art mass spectrometry and genetically engineered mouse models representing preinvasive or early, organ-confined stages of pancreatic neoplasia to identify a comprehensive set of biomarkers that can be used in combination to prospectively diagnose early neoplasic disease in humans. In Aim 1, we will identify serum biomarkers in genetically inbred mice that express an activated allele of Kras (KrasG12D) in the pancreatic ductal epithelium and in mice with KrasG12D expressed on a p16lnk4a- or p53-deficient background. Constitutive activation of KRAS is observed in over 90% of PDAC cases and it likely represents one of the earliest genetic lesions in pancreatic cancer. Aim 2 will utilize newly-derived pancreatic ductal cell lines from the same animal models described in Aim 1 to characterize the complete spectrum of changes that occur in the cell-surface proteome and in the secretome as neoplasia progresses from preinvasive lesions to fully metastatic disease. In Aim 3, we will utilize histology-guided MALDI-TOF MS tissue profiling to identify biomarkers associated with early-stage pancreatic neoplasia using pancreatic tissue from the animal models. From these results, we expect to compile a comprehensive set of biomarkers for detection of early-stage pancreatic cancer. Finally, in Aim 4, we will test the specificity and sensitivity of the early-stage biomarkers identified in the murine system for their ability to diagnose pancreatic neoplasia using human serum samples collected from healthy donors and cases representing chronic pancreatitis and PDAC. The goal of these studies will be the development of an antibody-based diagnostic assay that can be used to screen high-risk patients for pancreatic cancer.